Method for assembling integral type electronic device, and integral type electronic device

ABSTRACT

An integral type electronic device is formed from a first board and a second board by storing and holding electronic components in component storage parts of the first board, and then electrically connecting the second board to the electronic components. An arrangement accuracy of the electronic components is determined on a basis of an arrangement accuracy of the component storage parts, and the electronic components stored and held in the component storage parts are limited in motion.

This application is a Divisional of U.S. Ser. No. 09/940,876, filed Aug. 29, 2001.

BACKGROUND OF THE INVENTION

The present invention relates to a method for assembling an integral type electronic device which is manufactured by combining a plurality of electronic components in one body, and an integral type electronic device assembled by the method.

In response to recent advancement of making electronic devices small and light-weight, there has been proposed a large number of ways to further miniaturize electronic devices. Many of electronic devices manufactured by the proposed ways are formed by combining an electronic component having two or more functions with a device having one function.

Various mounting processes and facilities have been developed hitherto to arrange electronic components highly accurately with high reliability. A conventional method of assembling electronic components will be described below with reference to FIGS. 8-11.

Initially, conductive adhesive 2 is supplied onto a board 1 as shown in FIG. 8. Then, electronic components 3 are placed on portions of the conductive adhesive 2 as shown in FIG. 9 and fixed to the conductive adhesive 2 with hardening of the conductive adhesive 2. After conductive adhesive 4 is supplied onto the electronic components 3 as shown in FIG. 10, a board 5 is placed on the conductive adhesive 4 as shown in FIG. 11. The conductive adhesive 4 is then hardened, whereby an integral type electronic component 6 is formed.

With the conventional method as described above, mounting of each of the components onto the board 1 is required, and therefore, the method is not suitable for devices requiring a mounting accuracy, for example, for mounting optical components necessitating an optical path alignment, and the like. The electronic components 3 undesirably vary in height from the board 1 because the electronic components 3 are placed on the conductive adhesive 2. As a result, when the board 5 is mounted onto the electronic components 3 during a subsequent step, a so-called open fault, in which the electronic components 3 and the board 5 are not electrically connected with each other, possibly arises. Further, in a case where there are many electronic components 3 to be mounted, it takes a long time before all the components 3 are mounted completely, and also there are problems in that a quality of mounting of the components on the conductive adhesive 2 deteriorates and a cost increases because of a long manufacturing time.

SUMMARY OF THE INVENTION

The present invention is devised to solve the above problems and has for its object to provide an easy, high-quality and low-cost method for assembling an integral type electronic device, and an integral type electronic device assembled by the method.

In order to accomplish the above and other objects, there is provided a method for assembling an integral type electronic device according to a first aspect of the present invention, which comprises:

-   -   storing and holding an electronic component in a component         storage part (opening) of a first board; and     -   electrically connecting a second board to the electronic         component stored and held in the component storage part of the         first board, thereby forming an integral type electronic device         including the first board and the second board.

Bumps of the second board may be flattened before the second board is electrically connected to the electronic component after the electronic component is stored and held in the component storage part of the first board.

An integral type electronic device is provided according to a second aspect of the present invention, which comprises:

-   -   a first board with a component storage part (opening) for         storing and holding an electronic component; and     -   a second board which is electrically connected to the electronic         component stored and held in the component storage part of the         first board, thereby being united with the first board.

In the second aspect, when the electronic component is a light-emitting element, the component storage part may be formed to have a side wall for shielding light of the light-emitting element.

In the second aspect, the first board can be formed of any one of glass, ceramic and an organic resin.

In the second aspect, the electronic component may be held in the component storage part with a photo-curing type insulating resin.

According to the assembling method for the integral type electronic device of the first aspect of the present invention, and the integral type electronic device of the second aspect, the second board is electrically connected to electronic components after the electronic components are stored and held in component storage parts (openings) of the first board. Therefore, an arrangement accuracy of the electronic components is determined on a basis of an arrangement accuracy of the component storage parts of the first board. Also, the electronic components stored and held in the component storage parts are restricted in motion. Furthermore, since it is sufficiently simple to insert the electronic components in the component storage parts, a long time is not required to complete mounting as compared with the conventional art, even if a lot of electronic components are to be mounted. Manufacturing time is shortened and costs can be reduced in comparison with the conventional art.

The electronic components can be arranged highly accurately and simply at low costs in comparison with the conventional art.

The so-called open fault can be avoided by flattening bumps of the second board.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view of a first board which is used for carrying out a method for assembling an integral type electronic device, according to an embodiment of the present invention;

FIG. 2 is a sectional view of the first board indicating a state with electronic components filled in component storage parts of the first board;

FIG. 3 is a sectional view of the first board indicating a state in which electronic components filled in the first board are fixed with an adhesive;

FIG. 4 is a side view of a second board to be fitted to the first board;

FIG. 5 is a diagram showing a state in which the first board, having electronic components fixed with the adhesive, and the second board are joined;

FIG. 6 is a diagram of a state in which a third board is joined to a product obtained by joining the first board to the second board;

FIG. 7 is a flow chart explanatory of the method for assembling an integral type electronic device according to the embodiment of the present invention;

FIG. 8 is a diagram showing a state with a conductive adhesive supplied to a board, which is used for carrying out a conventional method for assembling an integral type electronic device;

FIG. 9 is a diagram of a state with components mounted to the conductive adhesive;

FIG. 10 is a diagram of a state with a conductive adhesive supplied to upper parts of the components; and

FIG. 11 is a diagram of a state with a board mounted to an upper part of the conductive adhesive supplied to the upper parts of the components.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A method for assembling an integral type electronic device, and an integral type electronic device assembled by the integral type electronic component assembling method, which are embodiments of the present invention will be described below with reference to the drawings. Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals.

The integral type electronic component assembling method is carried out in a manner as will be discussed below.

In a step S1 of FIG. 7, component storage parts (openings) 102 are formed by dry etching or wet etching a first board 101 as shown in FIG. 1. Each of the component storage parts 102 is a recessed part in which an electronic component 103 to be described below can be stored. Each component storage part may be a bottomed shape or can be, e.g., a through hole penetrating in a thickness direction of the first board 101 as indicated in FIG. 1. Although a plurality of the component storage parts 102 are formed in the first board 101 in FIG. 1, there may be formed one storage part from a relationship with an electronic component 103 to be stored. The component storage part 102 is necessary to be larger by, for instance, 5-30 μm than the electronic component 103 to be stored. For example, an Si substrate, a glass substrate, a ceramic substrate, an organic resin material substrate or the like is used as the first board 101. The storage parts 102 are parallel to each other such that when plural electronic components 103 are received within plural component storage parts, the electronic components are also parallel to each other.

A crystal orientation of Si may be any of (1,1,1), (1,0,0) and (1,1,0) when an Si substrate is used.

In a next step S2, as shown in FIG. 2, electronic components 103 are disposed within the component storage parts 102. Each electronic component 103 corresponds to, for example, a light-emitting element such as an LED (light-emitting diode) or the like, an IC of an Si substrate, an IC of a GaAs substrate, a resistor, a capacitor or the like. For an electronic component 103 being, e.g., an LED, an orientation of the LED is controlled by a mounting machine having a recognition function, so that the LED is stored in a component storage part 102 with a light-emitting part of the LED directed downwardly in the drawing. Although the electronic components 103 are placed in all of the component storage parts 102 in FIG. 2, the present embodiment is not limited to this arrangement and the electronic component(s) 103 is sometimes placed in only some of the component storage parts 102 in relation to a circuit design.

When the electronic component 103 is a light-emitting element such as an LED or the like, the component storage part 102 may be formed to have a side wall 1012 for shielding light of the light-emitting element. The side wall 1012 can prevent, for example, interference due to light emitted from an adjoining LED from arising.

In a succeeding step S3, as shown in FIG. 3, an insulating adhesive 104 is filled and then cured in each component storage part 102 with an electronic component 103 stored therein. An adhesive of a type cured with ultraviolet rays, a thermosetting type adhesive or the like can be used as an example of the insulating adhesive 104. When an adhesive to be cured with ultraviolet rays is used, for instance, the adhesive is cured by applying ultraviolet rays after the adhesive is filled into the component storage parts.

In a next step S4, gold bumps 106 are formed correspondingly to electronic components 103 on a second board 105 which is to be electrically connected to the electronic components 103. In a next step S5, it is decided whether or not leading end parts of the gold bumps 106 of the second board 105 are to be flattened. When flattening is determined to be necessary, the method proceeds to a next step S6 and flattening is carried out. Then the method proceeds to a next step S7. On the other hand, when flattening is determined to be unnecessary, the method skips step S6 and proceeds to step S7. Whether flattening is necessary or not may be judged by a worker.

During step S7 as shown in FIG. 4, a conductive adhesive 107 is applied to leading end parts of the gold bumps 106 on the second board 105. The second board 105 may be a semiconductor chip of, e.g., Si, GaAs, InP or the like. During step S7, the first board 101 with the electronic components 103 and the second board 105 with the gold bumps 106 are aligned so as to cause the electronic components 103 and the gold bumps 106 to contact each other, as indicated in FIG. 5. Then the first board 101 and the second board 105 are fitted to each other. After this fitting, the conductive adhesive 107 is cured, thereby joining the first board 101 to the second board 105. A first integral type electronic component 110 is formed in this manner.

According to the present embodiment, further during a step S8, a third board 108 is joined with a conductive adhesive 109 to the above-joined first board 101 and second board 105. A second integral type electronic component 111 may be accordingly formed as shown in FIG. 6.

The assembling method for the integral type electronic component, and the integral type electronic component assembled by the method can exert the following effects. It has conventionally been a problem as to how, without the first board 101, assemble small components while fixedly transferring the components. That is, a process related to arranging and fixing components has been complicated in the conventional art, thereby raising problems of a yield decrease, and the like. In contrast to this, according to the present embodiment, an arrangement accuracy of electronic components 103 is determined on a basis of an arrangement accuracy of component storage parts 102 formed in the first board 101. Moreover, the electronic components 103 stored in the component storage parts 102 are limited in motion. In order to arrange the electronic components 103, it is sufficient only to insert the electronic components 103 into the component storage parts 102. Arrangement is thus made simple. Mounting will be completed in a shorter time as compared with the conventional art even if there is a large number of electronic components 103 to be mounted. Manufacturing time is shortened and costs can be reduced in comparison with the conventional art.

Arrangement of the electronic components 103 is realized highly accurately and simply at low costs in comparison with the conventional art.

Additionally, an open fault is prevented because the bumps 106 on the second board 105 are flattened.

Although the present invention has been fully described in connection with the preferred embodiment thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom. 

1. An integral electronic device comprising: a first board having an opening that extends completely through a thickness of said first board; an electronic component held within said opening; and a second board electrically connected to said electronic component.
 2. The integral electronic device according to claim 1, wherein said electronic component comprises a light-emitting element and said opening is defined by a side wall that is capable of shielding light emitted from said light-emitting element.
 3. The integral electronic device according to claim 2, wherein said first board comprises a board of any one of glass, ceramic and an organic resin.
 4. The integral electronic device according to claim 3, wherein said light-emitting element is held within said opening via a photo-curing insulating resin.
 5. The integral electronic device according to claim 2, wherein said light-emitting element is held within said opening via a photo-curing insulating resin.
 6. The integral electronic device according to claim 1, wherein said first board comprises a board of any one of glass, ceramic and an organic resin.
 7. The integral electronic device according to claim 6, wherein said electronic component is held within said opening via a photo-curing insulating resin.
 8. The integral electronic device according to claim 1, wherein said electronic component is held within said opening via a photo-curing insulating resin.
 9. The integral electronic device according to claim 1, wherein said second board is electrically connected to said electronic component via a flat metallic bump.
 10. The integral electronic device according to claim 1, wherein said electronic component is held within said opening via an insulating resin that surrounds said electronic component except for upper and lower surfaces of said electronic component.
 11. The integral electronic device according to claim 10, wherein said second board is electrically connected to said electronic component by being electrically connected to said upper surface of said electronic component, said integral electronic device further comprising: a third board electrically connected to said lower surface of said electronic component.
 12. The integral electronic device according to claim 1, further comprising: another electronic component held within another opening that extends completely through the thickness of said first board, wherein said second board is electrically connected to said another electronic component, with said opening and said another opening being parallel to one another. 